[Toybox] You've seen the /dev/random shenanigans, right?

[enh]

On Tue, Sep 19, 2023 at 2:48 PM Eric Biggers <ebiggers at google.com> wrote:
>
> On Tue, Sep 19, 2023 at 12:44:17PM -0700, enh wrote:
> > > now writing to /dev/random not only doesn't credit entropy (so it
> > > still blocks)
>
> It's always been like that, at least back to the earliest git commit in Linux
> history (dated 2005).  The only way for userspace programs to credit entropy has
> always been the RNDADDENTROPY and RNDADDTOENTCNT ioctls.
>
> > > but has an arbitrary delay about even mixing the data in.
>
> This has been the case since Linux v4.8, released in 2016.  v5.18 (released in
> 2022) stopped pretending to care about the "premature next" security model and
> therefore reseeds the CRNG more frequently, and even makes writes to
> /dev/{u,}random take effect immediately in some (but not all) cases.  This
> improved on the behavior you're complaining about, which again was introduced in
> 2016.  IIRC there are still reasons for not making writes to /dev/{u,}random
> *always* take effect immediately, but I can bring it up on the list again.

in the meantime, should EntropyMixer be using the ioctl? or does it
not actually matter in this case?

> - Eric